A method, apparatus and device for detecting urea crystallization

Abstract

The application discloses a method, device and equipment for detecting urea crystallization. According to the pressure difference between the front-end pressure and the rear-end pressure of a DPF system and the pressure difference between the front-end pressure of the DPF system and the atmospheric pressure, the relative pressure difference of the SCR system can be obtained through the three-way pipeline and the valve in the equipment. Whether the urea crystallizes is determined based on the relative pressure difference and the preset pressure difference. For example, when the relative pressure difference is too large, it indicates that the urea crystallization blocks the pipeline, thereby increasing the relative pressure difference. The method can more accurately detect the urea crystallization state of the SCR system, avoids the problem of increased fuel consumption caused by the regeneration when there is no urea crystallization, and avoids the problem of the SCR system blockage caused by no regeneration when the crystallization is fast.

Description

Technical Field

[0001] This application relates to the field of exhaust emission technology, and in particular to a method, apparatus and equipment for detecting urea crystals. Background Technology

[0002] To meet increasingly stringent emission regulations, SCR (Selective Catalytic Reduction) technology has been widely adopted as an exhaust aftertreatment technology. Currently, diesel engine SCR systems commonly use urea aqueous solution as a reducing agent additive. Due to the inherent properties of urea aqueous solution, its incomplete decomposition in the pipeline can lead to crystallization. With the upgrading of emission regulations, the proportion of emissions from diesel engines operating at low speeds and low loads is increasing, and the trend towards lower exhaust temperatures makes urea crystallization and blockage in SCR systems more frequent.

[0003] Current technologies typically involve setting mileage or frequency to regenerate and burn off crystals. However, manually controlling the regeneration frequency often fails to accurately identify the crystallization status of the SCR system. This can lead to increased fuel consumption if regeneration is performed when no crystals are present, or rapid crystallization without regeneration, resulting in clogging of the aftertreatment system. Therefore, accurately detecting urea crystallization in the SCR system has become a pressing issue that needs to be addressed. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a method, apparatus, and equipment for detecting urea crystals, in order to accurately detect urea crystals in an SCR system.

[0005] This application discloses a method for detecting urea crystals, the method comprising:

[0006] Obtain the first pressure difference; the first pressure difference is the pressure difference between the front-end air pressure of the DPF system and the back-end air pressure of the DPF system;

[0007] Obtain the second pressure difference; the second pressure difference is the pressure difference between the front-end air pressure of the DPF system and atmospheric pressure;

[0008] The relative pressure difference of the SCR system is obtained by subtracting the first pressure difference from the second pressure difference.

[0009] Based on the relative pressure difference and the preset pressure difference, it is determined whether urea crystallizes.

[0010] Optionally, before obtaining the first differential pressure, the method further includes:

[0011] Install valves to control the range of differential pressure acquisition;

[0012] Determine whether the current operating conditions meet the requirements for crystallization detection;

[0013] If so, the valve is controlled to be in a crystallization detection state;

[0014] If not, then the valve is controlled to be in the working state.

[0015] Optionally, determining whether the current operating condition meets the crystallization detection conditions includes:

[0016] When the distance between the vehicle and the last crystallization detection mileage is greater than a preset mileage, the temperature at the front end of the SCR system is obtained;

[0017] Obtain the first exhaust gas volume flow rate, and obtain the second exhaust gas volume flow rate after a preset time;

[0018] Determine whether the temperature is greater than a preset temperature, whether the first exhaust gas volume flow rate is greater than a first preset flow rate and less than the difference between the second exhaust gas volume flow rate and the first exhaust gas volume flow rate, and whether the difference is less than the second preset flow rate.

[0019] If so, then the current operating conditions are deemed to meet the crystallization detection requirements;

[0020] If not, then the current operating conditions do not meet the requirements for crystallization detection.

[0021] Optionally, determining whether urea has crystallized based on the relative pressure difference and a preset pressure difference includes:

[0022] Determine whether the relative pressure difference is greater than a preset pressure difference;

[0023] If so, it is determined that urea crystals are present, causing the relative pressure difference to increase, and that urea crystals are present.

[0024] If not, it is determined that the relative pressure difference was not affected by urea crystallization, and urea did not crystallize.

[0025] Optionally, after determining whether urea has crystallized, the method further includes:

[0026] When it is determined that urea crystals are present, regeneration is triggered to burn off the urea crystals, and the valve is controlled to be in the working state.

[0027] When it is determined that there is no crystallization in the urea, the valve is controlled to be in the working state.

[0028] Based on the above-mentioned method for detecting urea crystals, this application also discloses an apparatus for detecting urea crystals, comprising: a first differential pressure acquisition unit, a second differential pressure acquisition unit, a relative differential pressure acquisition unit, and a crystallization judgment unit;

[0029] The first differential pressure acquisition unit is used to acquire a first differential pressure; the first differential pressure is the pressure difference between the front-end air pressure of the DPF system and the back-end air pressure of the DPF system.

[0030] The second differential pressure acquisition unit is used to acquire a second differential pressure; the second differential pressure is the pressure difference between the front-end air pressure of the DPF system and atmospheric pressure.

[0031] The relative pressure difference acquisition unit is used to subtract the first pressure difference from the second pressure difference to obtain the relative pressure difference of the SCR system.

[0032] The crystallization determination unit is used to determine whether urea has crystallized based on the relative pressure difference and the preset pressure difference.

[0033] Optionally, the device further includes: a valve setting unit, a detection and judgment unit, a detection start unit, and a valve working unit;

[0034] The valve setting unit is used to set the valve to control the differential pressure acquisition range;

[0035] The detection and judgment unit is used to determine whether the current working condition meets the crystallization detection conditions;

[0036] The detection start unit is used to control the valve to be in the crystallization detection state;

[0037] The valve working unit is used to control the valve to be in working state.

[0038] Optionally, the detection and judgment unit includes:

[0039] The temperature acquisition subunit is used to acquire the temperature of the front end of the SCR system when the distance between the vehicle and the last crystallization detection mileage is greater than a preset mileage;

[0040] The flow acquisition subunit is used to acquire the first exhaust gas volume flow rate and acquire the second exhaust gas volume flow rate after a preset time.

[0041] The condition judgment subunit is used to determine whether the temperature is greater than a preset temperature, whether the first exhaust gas volume flow rate is greater than a first preset flow rate and less than the difference between the second exhaust gas volume flow rate and the first exhaust gas volume flow rate and less than the second preset flow rate.

[0042] The result output subunit is used to determine whether the current operating condition meets the crystallization detection conditions.

[0043] Used to determine if the current operating conditions do not meet the requirements for crystallization detection.

[0044] Optionally, the crystallization determination unit includes:

[0045] The differential pressure judgment subunit is used to determine whether the relative differential pressure is greater than a preset differential pressure.

[0046] There is a crystallization judgment subunit, which is used to determine whether the presence of urea crystallization increases the relative pressure difference, indicating that urea crystallizes.

[0047] The non-crystallization judgment subunit is used to determine that the relative pressure difference is not affected by urea crystallization and that urea is not crystallizing.

[0048] Optionally, the device further includes:

[0049] The regeneration unit is used to trigger regeneration to burn off the urea crystals when it is determined that urea has crystals, and to control the valve to be in working condition.

[0050] The valve return unit is used to control the valve to be in working state when it is determined that there is no crystallization of urea.

[0051] Based on the above-mentioned method for detecting urea crystals, this application also discloses an apparatus for detecting urea crystals, comprising: a three-way pipe and a valve;

[0052] The three-way pipe is connected to the front gas intake pipe of the DPF system, the rear gas intake pipe of the DPF system, and the atmosphere, respectively.

[0053] The valve is located between the three-way pipe that connects to the atmosphere and the gas intake pipe that connects to the back end of the DPF system.

[0054] Optionally, the state of the valve is controlled by an electronic control unit, which controls the connection of the three-way pipe to the gas intake pipe at the back end of the DPF system or to the atmosphere.

[0055] Optionally, the device further includes:

[0056] Differential pressure sensor, used to obtain air pressure difference value.

[0057] Optionally, the tee pipe may also include:

[0058] A filter screen is installed at the location where the three-way pipe connects to the atmosphere;

[0059] The filter is used to prevent impurities in the air from contaminating the differential pressure sensor and SCR system.

[0060] This application discloses a method, apparatus, and device for detecting urea crystallization. Through the three-way pipe and valves in the device described in this application, the relative pressure difference of the SCR system can be obtained based on the pressure difference between the front and rear ends of the DPF system, and the pressure difference between the front end of the DPF system and atmospheric pressure. Based on the relative pressure difference and a preset pressure difference, it is determined whether urea has crystallized. For example, when the relative pressure difference is too large, it indicates that urea crystallization is blocking the pipeline, thus increasing the relative pressure difference. The method described in this application can more accurately detect the urea crystallization state of the SCR system, avoiding the increased fuel consumption caused by regeneration when there is no urea crystallization, and the SCR system blockage caused by rapid crystallization without regeneration. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0062] Figure 1 This is a schematic flowchart of a method for detecting urea crystals disclosed in an embodiment of this application;

[0063] Figure 2 This is a schematic flowchart of another method for detecting urea crystals disclosed in an embodiment of this application;

[0064] Figure 3 This is a schematic diagram of the structure of a device for detecting urea crystals disclosed in an embodiment of this application;

[0065] Figure 4 This is a schematic diagram of the structure of a device for detecting urea crystals disclosed in an embodiment of this application;

[0066] Figure 5a This is a schematic diagram of the structure of a device for detecting urea crystals disclosed in an embodiment of this application in its working state;

[0067] Figure 5b This is a schematic diagram of the structure of a device for detecting urea crystals disclosed in an embodiment of this application in the crystal detection state. Detailed Implementation

[0068] Scenario Introduction: In a vehicle's exhaust system, there are DPF (Diesel Per Filter) and SCR (Selective Catalytic Reduction) systems. The airflow direction is from the DPF system to the SCR system; therefore, the rear end of the DPF system connects to the front end of the SCR system. Next to the DPF system, there is a differential pressure sensor used to acquire the pressure difference between the front and rear ends of the DPF system. The method for detecting urea crystals described in this application is implemented using a device for detecting urea crystals. The device has a three-way pipe connected to the front and rear ends of the DPF system and the atmosphere. In other words, the three-way pipe is an additional pipe connected to the atmosphere on top of the differential pressure sensor. Changing the position of the valve in the device can control the three-way pipe to connect the front and rear ends of the DPF system or connect the front end of the DPF system to the atmosphere.

[0069] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0070] Example 1: This application discloses a method for detecting urea crystals.

[0071] For details, please refer to Figure 1 The method for detecting urea crystals disclosed in this embodiment includes the following steps:

[0072] Step 101: Obtain the first pressure difference; the first pressure difference is the pressure difference between the front-end air pressure of the DPF system and the back-end air pressure of the DPF system.

[0073] In the method described in this embodiment, as an optional approach, a valve is first set to control the differential pressure acquisition range. It is then determined whether the current operating conditions meet the crystallization detection conditions. If so, the valve is controlled to be in the crystallization detection state. If not, the valve is controlled to be in the working state. Specifically, the valve's crystallization detection state controls the differential pressure acquisition range to be between the DPF system's front-end air pressure and atmospheric pressure, while the valve's working state controls the differential pressure acquisition range to be between the DPF system's front-end air pressure and the DPF system's rear-end air pressure.

[0074] One optional method for determining whether the current operating condition meets the crystallization detection conditions is to first record the vehicle's mileage. When the mileage since the last crystallization detection exceeds a preset mileage, the temperature at the front end of the SCR system and the exhaust gas volumetric flow rate are acquired as the first exhaust gas volumetric flow rate. After a preset time, the exhaust gas volumetric flow rate is acquired again as the second exhaust gas volumetric flow rate. The absolute value of the difference between the two exhaust gas volumetric flow rates is calculated as the change value. Then, it is determined whether the temperature is greater than a preset temperature, whether the first acquired exhaust gas volumetric flow rate is greater than the first preset flow rate, and whether the change value is less than the second preset flow rate. If all three conditions are met, the current operating condition is deemed to meet the crystallization detection conditions. If any one of these conditions is not met, the current operating condition is deemed not to meet the crystallization detection conditions.

[0075] The preset mileage, preset temperature, first preset flow rate, and second preset flow rate can all be set according to user needs. The specific values ​​of these preset values ​​are not limited here, as long as they can achieve the method described in this embodiment.

[0076] In the method described in this embodiment, the valve is in the working state, and the first differential pressure it obtains is as shown in Formula 1:

[0077] P1＝ P 前 -P 后 (1)

[0078] Where P1 is the first pressure difference, P 前 P is the front-end air pressure of the DPF system. 后 This refers to the back-end air pressure of the DPF system.

[0079] Step 102: Obtain the second pressure difference; the second pressure difference is the pressure difference between the front-end air pressure of the DPF system and the atmospheric pressure.

[0080] In the method described in this embodiment, the valve is in a crystallization detection state, and the second differential pressure it obtains is as shown in Formula 2:

[0081] P 2＝ P 前 -P a (2)

[0082] Where P2 is the second pressure difference, P a Atmospheric pressure.

[0083] Step 103: Subtract the first pressure difference from the second pressure difference to obtain the relative pressure difference of the SCR system.

[0084] In the method described in this embodiment, the obtained relative pressure difference is as shown in Formula 3:

[0085] P s＝ P2-P1 (3)

[0086] Among them, P s This represents the relative pressure difference.

[0087] Substituting formulas (1) and (2) into formula (3), we get:

[0088] P s =P 后 -P a (4)

[0089] In the method described in this embodiment, the DPF system is connected to the SCR system. Therefore, the pressure at the back end of the DPF system is the same as the pressure at the front end of the SCR system. Thus, the relative pressure difference can be regarded as the difference between the pressure at the front end of the SCR system and atmospheric pressure.

[0090] Step 104: Based on the relative pressure difference and the preset pressure difference, determine whether urea has crystallized.

[0091] In the method described in this embodiment, the formation of urea crystals will block the exhaust pipe, thereby increasing the pressure at the back end of the DPF system (that is, the pressure at the front end of the SCR system), while atmospheric pressure is constant, thus increasing the relative pressure difference.

[0092] As an alternative method, based on the above principle, it can be determined whether the relative pressure difference is greater than the preset pressure difference. If it is, it is determined that urea crystals are present, causing the relative pressure difference to increase, indicating that urea crystals are present. If not, it is determined that the relative pressure difference is not affected by urea crystals, indicating that urea does not crystallize. It is possible that a very small amount of urea crystals are present even when the relative pressure difference is not affected by urea crystals, but since this does not affect the relative pressure difference, it can be determined that urea does not crystallize.

[0093] In the method described in this embodiment, as an optional approach, when it is determined that urea crystals are present, regeneration is triggered to burn off the urea crystals, and the valve is controlled to be in the working state. When it is determined that no urea crystals are present, the valve is controlled to return from the crystallization detection state to the working state, in preparation for the next crystallization detection.

[0094] As an alternative method, when urea crystallization is detected, a regeneration reminder is sent to the user. After the user initiates regeneration, the control valve is activated. When no urea crystallization is detected, the control valve is activated, and a reminder indicating that regeneration is not required is sent to the user. The reminder can be text or voice, as long as it serves its purpose; no specific limitation is made on the method. This method provides users with the opportunity to actively operate, deciding whether to perform regeneration based on their needs, making it more user-friendly.

[0095] The method described in this embodiment can determine whether to perform urea crystallization detection based on parameters such as mileage, temperature, and gas flow rate, avoiding the problem of overly frequent or infrequent detection due to a single strategy for controlling urea crystallization detection. Once crystallization detection begins, the relative pressure difference of the SCR system is obtained through an added three-way pipeline and a controllable valve. Based on the principle that urea crystallization blocks the exhaust pipe, increasing the relative pressure difference, the urea crystallization status of the SCR system can be accurately identified. Subsequently, regeneration is triggered according to the severity of urea crystallization, avoiding SCR system blockage caused by untimely regeneration and increased fuel consumption due to unnecessary regeneration.

[0096] Example 2: This application discloses another method for detecting urea crystals; please refer to [link / reference]. Figure 2 This embodiment describes the complete process of urea crystallization detection and regeneration triggering.

[0097] Step 201: Determine whether the current operating conditions meet the crystallization detection requirements. If yes, proceed to step 202. Otherwise, repeat step 201.

[0098] Step 202: Obtain the first differential pressure and control the valve to change from the working state to the crystallization detection state.

[0099] In the method described in this embodiment, the first pressure difference is the pressure difference between the front-end air pressure of the DPF system and the back-end air pressure of the DPF system.

[0100] Step 203: Obtain the second pressure difference.

[0101] In the method described in this embodiment, the second pressure difference is the pressure difference between the front-end air pressure of the DPF system and atmospheric pressure.

[0102] Step 204: Subtract the first pressure difference from the second pressure difference to obtain the relative pressure difference of the SCR system.

[0103] According to formula (4), the relative pressure difference is the difference between the pressure at the back end of the DPF system (the pressure at the front end of the SCR system) and the atmospheric pressure.

[0104] Step 205: Determine if the relative pressure difference is greater than the preset pressure difference. If yes, determine that urea has crystallized and proceed to step 206. If no, determine that urea has not crystallized and proceed to step 207.

[0105] In the method described in this embodiment, as an optional method, a reminder that regeneration is not required can also be sent to the user after it is determined that no urea crystallization has occurred.

[0106] Step 206: Trigger regeneration to burn off urea crystals. Proceed to step 207.

[0107] In the method described in this embodiment, as an optional approach, a regeneration reminder can be sent to the user first, and regeneration can be triggered only after the user confirms. This provides the user with an opportunity to take initiative and decide whether to perform regeneration based on the user's needs, making it more user-friendly.

[0108] Step 207: Control the valve to return to the working state, in preparation for the next crystallization test.

[0109] The method described in this embodiment obtains the relative pressure difference of the SCR system through an added three-way pipeline and a controllable valve. Based on the principle that urea crystallization blocking the exhaust pipe increases the relative pressure difference, the urea crystallization status of the SCR system can be accurately identified. Subsequently, regeneration is triggered according to the severity of urea crystallization, avoiding SCR system blockage caused by untimely regeneration and unnecessary increases in fuel consumption due to regeneration.

[0110] Based on the method for detecting urea crystals disclosed in the above embodiments, this embodiment correspondingly discloses an apparatus for detecting urea crystals. Please refer to... Figure 3 The device for detecting urea crystals includes: a first differential pressure acquisition unit 301, a second differential pressure acquisition unit 302, a relative differential pressure acquisition unit 303, and a crystallization judgment unit 304;

[0111] The first differential pressure acquisition unit 301 is used to acquire a first differential pressure; the first differential pressure is the pressure difference between the front-end air pressure of the DPF system and the back-end air pressure of the DPF system.

[0112] The second differential pressure acquisition unit 302 is used to acquire a second differential pressure; the second differential pressure is the pressure difference between the front-end air pressure of the DPF system and atmospheric pressure.

[0113] The relative pressure difference acquisition unit 303 is used to subtract the first pressure difference from the second pressure difference to obtain the relative pressure difference of the SCR system.

[0114] The crystallization judgment unit 304 is used to determine whether urea has crystallized based on the relative pressure difference and the preset pressure difference.

[0115] Optionally, the device further includes: a valve setting unit, a detection and judgment unit, a detection start unit, and a valve working unit;

[0116] The valve setting unit is used to set the valve to control the differential pressure acquisition range;

[0117] The detection and judgment unit is used to determine whether the current working condition meets the crystallization detection conditions;

[0118] The detection start unit is used to control the valve to be in the crystallization detection state;

[0119] The valve working unit is used to control the valve to be in working state.

[0120] Optionally, the detection and judgment unit includes:

[0121] The temperature acquisition subunit is used to acquire the temperature of the front end of the SCR system when the distance between the vehicle and the last crystallization detection mileage is greater than a preset mileage;

[0122] The flow acquisition subunit is used to acquire the first exhaust gas volume flow rate and acquire the second exhaust gas volume flow rate after a preset time.

[0123] The condition judgment subunit is used to determine whether the temperature is greater than a preset temperature, whether the first exhaust gas volume flow rate is greater than a first preset flow rate and less than the difference between the second exhaust gas volume flow rate and the first exhaust gas volume flow rate and less than the second preset flow rate.

[0124] The result output subunit is used to determine whether the current operating condition meets the crystallization detection conditions.

[0125] Used to determine if the current operating conditions do not meet the requirements for crystallization detection.

[0126] Optionally, the crystallization determination unit 304 includes:

[0127] The differential pressure judgment subunit is used to determine whether the relative differential pressure is greater than a preset differential pressure.

[0128] There is a crystallization judgment subunit, which is used to determine whether the presence of urea crystallization increases the relative pressure difference, indicating that urea crystallizes.

[0129] The non-crystallization judgment subunit is used to determine that the relative pressure difference is not affected by urea crystallization and that urea is not crystallizing.

[0130] Optionally, the device further includes:

[0131] The regeneration unit is used to trigger regeneration to burn off the urea crystals when it is determined that urea has crystals, and to control the valve to be in working condition.

[0132] The valve return unit is used to control the valve to be in working state when it is determined that there is no crystallization of urea.

[0133] Based on the method for detecting urea crystals disclosed in the above embodiments, this embodiment correspondingly discloses a device for detecting urea crystals. Please refer to... Figure 4 The device for detecting urea crystals includes: a three-way pipe 401 and a valve 402;

[0134] The three-way pipe 401 is connected to the front gas intake pipe of the DPF system, the rear gas intake pipe of the DPF system, and the atmosphere, respectively.

[0135] The valve 402 is located between the three-way pipe 401, which connects to the atmosphere, and the gas intake pipe at the back end of the DPF system.

[0136] Optionally, the state of the valve 402 is controlled by an electronic control unit, which controls the connection of the three-way pipe 401 to the gas intake pipe at the back end of the DPF system or to the atmosphere.

[0137] Optionally, the device further includes:

[0138] Differential pressure sensor, used to obtain air pressure difference value.

[0139] Optionally, the tee pipe 401 may also include:

[0140] A filter screen is installed at the location where the three-way pipe 401 connects to the atmosphere;

[0141] The filter is used to prevent impurities in the air from contaminating the differential pressure sensor and SCR system.

[0142] As an optional method, in the device described in this embodiment, valve 402 is controlled by ECU (Electronic Control Unit).

[0143] This embodiment discloses the working mode of a device for detecting urea crystals. Please refer to [link / reference]. Figure 5a :

[0144] The differential pressure sensor 504 is connected to the front air intake pipe, the rear air intake pipe and the atmosphere of the DPF system 505 through a three-way pipe 501. A filter screen 503 is installed at the position where the connection to the atmosphere is made. The valve 502 is located between the three-way pipe 501 connecting the rear air intake pipe of the DPF system 505 and the position where the connection to the atmosphere is made.

[0145] At this time, the equipment is in working mode, valve 502 is in working condition, and the control tee pipe 501 is only connected to the front and rear air intake pipes of the DPF system 505. At this time, the airflow direction in the tee pipe 501 is from the rear end of the DPF system 505 to the differential pressure sensor 504. Therefore, the value obtained by the differential pressure sensor 504 is the air pressure difference between the front and rear air pressures of the DPF system 505.

[0146] This embodiment discloses a crystallization detection mode of an apparatus for detecting urea crystals. Please refer to [link to relevant documentation]. Figure 5b :

[0147] In crystallization detection mode, the equipment valve is in crystallization detection state, and the control tee pipe 501 is only connected to the atmosphere and the front gas intake pipe of the DPF system 505. At this time, the airflow direction in the tee pipe 501 is from the atmosphere to the differential pressure sensor 504. Therefore, the value obtained by the differential pressure sensor 504 is the pressure difference between the front gas pressure of the DPF system 505 and the atmospheric pressure.

[0148] The embodiments in this specification are described in a progressive manner. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant details can be found in the method section.

[0149] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0150] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0151] The features described in the embodiments of this specification can be substituted for or combined with each other, so that those skilled in the art can implement or use this application.

[0152] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A detection method for an apparatus used to detect urea crystals, characterized in that, The device for detecting urea crystals includes: a three-way pipe and a valve; the three-way pipe is respectively connected to the front gas intake pipe of the DPF system, the rear gas intake pipe of the DPF system, and the atmosphere; the valve is located between the three-way pipe connected to the atmosphere and the valve connected to the rear gas intake pipe of the DPF system; a differential pressure sensor is connected to the front gas intake pipe, the rear gas intake pipe, and the atmosphere of the DPF system through the three-way pipe, and the differential pressure sensor is used to acquire the gas pressure difference value; The detection method includes: Obtain the first pressure difference; the first pressure difference is the pressure difference between the front-end air pressure of the DPF system and the back-end air pressure of the DPF system, the relative pressure difference of the SCR system is the difference between the front-end air pressure of the SCR system and atmospheric pressure, and the DPF system is located upstream of the SCR system; Obtain the second pressure difference; the second pressure difference is the pressure difference between the front-end air pressure of the DPF system and the atmospheric pressure; The relative pressure difference of the SCR system is obtained by subtracting the first pressure difference from the second pressure difference. Based on the relative pressure difference and the preset pressure difference, it is determined whether urea crystallizes.

2. The detection method of the device for detecting urea crystals according to claim 1, characterized in that, Before obtaining the first differential pressure, the method further includes: Install valves to control the range of differential pressure acquisition; Determine whether the current operating conditions meet the requirements for crystallization detection; If so, the valve is controlled to be in a crystallization detection state; If not, then the valve is controlled to be in the working state.

3. The detection method of the device for detecting urea crystals according to claim 2, characterized in that, The determination of whether the current operating condition meets the crystallization detection conditions includes: When the distance between the vehicle and the last crystallization detection mileage is greater than a preset mileage, the temperature at the front end of the SCR system is obtained; Obtain the first exhaust gas volume flow rate, and obtain the second exhaust gas volume flow rate after a preset time; Determine whether the temperature is greater than a preset temperature, whether the first exhaust gas volume flow rate is greater than a first preset flow rate and less than the difference between the second exhaust gas volume flow rate and the first exhaust gas volume flow rate, and whether the difference is less than the second preset flow rate. If the judgment result is all yes, then the current working condition is judged to meet the crystallization detection conditions; If any of the judgment results are negative, then the current operating conditions are determined not to meet the crystallization detection conditions.

4. The detection method of the device for detecting urea crystals according to claim 1, characterized in that, The step of determining whether urea has crystallized based on the relative pressure difference and the preset pressure difference includes: Determine whether the relative pressure difference is greater than a preset pressure difference; If so, it is determined that urea crystals are present, causing the relative pressure difference to increase, and that urea crystals are present. If not, it is determined that the relative pressure difference was not affected by urea crystallization, and urea did not crystallize.

5. The detection method of the device for detecting urea crystals according to claim 2, characterized in that, After determining whether urea has crystallized, the method further includes: When it is determined that urea crystals are present, regeneration is triggered to burn off the urea crystals, and the valve is controlled to be in the working state. When it is determined that there is no crystallization in the urea, the valve is controlled to be in the working state.

6. The detection method of the device for detecting urea crystals according to claim 1, characterized in that, The valve's status is controlled by an electronic control unit, which controls whether the three-way pipe connects to the DPF system's back-end air intake pipe or to the atmosphere.

7. The detection method of the device for detecting urea crystals according to claim 1, characterized in that, The tee pipe also includes: A filter screen is installed at the location where the three-way pipe connects to the atmosphere; The filter is used to prevent impurities in the air from contaminating the differential pressure sensor and SCR system.

8. An apparatus for detecting urea crystals by performing the method of claim 1, characterized in that, include: The system comprises a first differential pressure acquisition unit, a second differential pressure acquisition unit, a relative differential pressure acquisition unit, and a crystallization judgment unit. The first differential pressure acquisition unit is used to acquire the first differential pressure; The first pressure difference is the pressure difference between the front-end pressure of the DPF system and the back-end pressure of the DPF system. The relative pressure difference of the SCR system is the difference between the front-end pressure of the SCR system and atmospheric pressure. The DPF system is located upstream of the SCR system. The second differential pressure acquisition unit is used to acquire the second differential pressure; The second pressure difference is the pressure difference between the front-end air pressure of the DPF system and atmospheric pressure; The relative pressure difference acquisition unit is used to subtract the first pressure difference from the second pressure difference to obtain the relative pressure difference of the SCR system. The crystallization determination unit is used to determine whether urea has crystallized based on the relative pressure difference and the preset pressure difference.

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